Presser bar lifter in a button perforating sewing machine

Abstract

A stop lever fixing lever supported at a bed body of a sewing machine has one end to be contacted by a projection of a pattern wheel. A connecting member has one end connected to the other end of the stop lever fixing lever. A first presser bar lifter has one end connected to the other end of the connecting member. A second presser bar lifter has one end defining an operation arm positioned at a lifting position and has a folded projection provided with a hole. A stepped screw having a knurled thumb at the peripheral surface thereof is rotatably inserted in the hole of the folded projection edge with a small diameter screw portion at the tip end thereof. A lever shifting member is screwed into the small diameter screw portion at the folded projection edge. A presser bar lifter cam is disposed along a cutting axis and has a projection. The lever shifting member is engaged with the first presser bar lifter at one pivotable position for transmitting the swingable movement of the first presser bar lifter to the second presser bar lifter while it is engaged with the projection of the presser bar lifter cam and at the other pivotable position transmits the swingably movement of the presser bar lifter cam to the second presser bar lifter.

What is claimed is: 
     
       1. A presser bar lifter in a button perforating sewing machine comprising: a pattern wheel fixed to a pattern wheel axis supported by a bed body of said sewing machine and rotatable through one revolution about the pattern wheel axis for each stiching operation cycle, said wheel having a projection positioned at a periphery thereof also rotatable through one revolution for each stitching operation;   a stop lever fixing lever supported by the bed body and having a central portion swingably supported by an axis parallel with the pattern wheel axis; one end to be kicked by the projection of the pattern wheel;   a connecting member having one end connected to another end of the stop lever fixing lever;   a first presser bar lifter having a middle portion swingably supported by a cutting axis parallel with the pattern wheel axis, one end connected to another end of the connecting member, the first presser bar lifter being always urged clockwise by a spring, extended between the stop lever fixing lever and the body, via the stop lever fixing lever and the connecting member;   a second presser bar lifter having a middle portion swingably supported at a side of the bed body by an axis parallel with the pattern wheel axis, one end defining an operation arm so as to be positioned at a lifting position by an urging force of a spring extended between the bed body and the second presser bar lifter, the other end provided with a folded projection inclined at a side of the operation arm and having a through hole;   a stepped screw having a knurled thumb at a peripheral surface thereof rotatably inserted in the through hole of the folded projection and a small diameter screw portion at a tip end thereof;   a lever shifting member screwed into the small diameter screw portion of the folded projection and having a projecting roller normally positioned in a recess of the second presser bar lever;   a presser bar lifter cam fixed to the cutting axis for swingably fixing the first presser bar lifter and having a projection;   the lever shifting member being engaged with the first presser bar lifter at one swingable position for transmitting the swingable movement of the first presser bar lifter to the second presser bar lifter and engaged with the projection of the presser bar lifter cam at another swingable position for transmitting the swingable movement of the presser bar lifter cam to the second presser bar lifter.   
     
     
       2. A presser bar lifter according to claim 1, wherein the first presser bar lifter has a recess at the end thereof for holding the projection at a state where the lever shifting member is swung in one swingable position whereby a movement of the first presser bar lifter is transmitted to the second pressor bar lifter via the lever shifting member. 
     
     
       3. A presser bar lifter according to claim 1, wherein the projection is held by the projection of the presser bar lifter cam at a state where the lever shifting member is swung in other swingable position whereby a movement of the projection is transmitted to the second presser lifter via the lever shifting member. 
     
     
       4. A presser bar lifter according to claim 1, wherein the stepped screw can fix the lever shifting member by a spline connection.